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Ch.21 - Transition Elements and Coordination Chemistry
All textbooksMcMurry 8th EditionCh.21 - Transition Elements and Coordination ChemistryProblem 123e
Chapter 21, Problem 123e

For each of the following, (i) give the systematic name of the compound and specify the oxidation state of the transition metal, (ii) draw a crystal field energy-level diagram and assign the d electrons to orbitals, (iii) indicate whether the complex is high-spin or low-spin (for d4 - d7 complexes), and (iv) specify the number of unpaired electrons.
(e) [Pt(NH3)4](ClO4)2

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Identify the central metal and its ligands in the complex. The complex is [Pt(NH3)4](ClO4)2, where Pt is the central metal and NH3 is the ligand.
Determine the oxidation state of the transition metal. The complex is neutral overall, and ClO4 is a -1 anion. Since there are two ClO4 ions, the total negative charge is -2. Therefore, the oxidation state of Pt must be +2 to balance the charge.
Name the compound systematically. The ligand NH3 is called 'ammine', and since there are four of them, it is 'tetraammine'. The metal is platinum, and with an oxidation state of +2, the name is 'tetraammineplatinum(II) perchlorate'.
Draw the crystal field energy-level diagram for a d8 metal ion like Pt(II). In an octahedral field, the d orbitals split into two sets: the lower energy t2g (dxy, dxz, dyz) and the higher energy eg (dx2-y2, dz2).
Assign the d electrons to the orbitals. Pt(II) has 8 d electrons. Fill the t2g orbitals first, then the eg orbitals. Since it is a d8 configuration, all orbitals will be filled, resulting in no unpaired electrons.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Coordination Compounds

Coordination compounds consist of a central metal atom bonded to surrounding molecules or ions called ligands. The nature of these bonds and the arrangement of ligands around the metal influence the compound's properties, including its color and magnetic behavior. Understanding the coordination number and geometry is essential for analyzing the complex's structure and reactivity.
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Coordination Compound Naming

Crystal Field Theory

Crystal Field Theory (CFT) explains the electronic structure of transition metal complexes by considering the effect of ligands on the d orbitals of the metal ion. According to CFT, the presence of ligands causes the degenerate d orbitals to split into different energy levels, which affects the distribution of electrons among these orbitals. This theory is crucial for determining the spin state of the complex and predicting its magnetic properties.
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The study of ligand-metal interactions helped to form Ligand Field Theory which combines CFT with MO Theory.

Spin States in Transition Metal Complexes

The spin state of a transition metal complex refers to the arrangement of electrons in the d orbitals, which can be either high-spin or low-spin. High-spin complexes have more unpaired electrons due to a weaker field strength from the ligands, while low-spin complexes have fewer unpaired electrons due to stronger field strength. The spin state significantly influences the magnetic properties and stability of the complex.
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Related Practice
Textbook Question

For each of the following, (i) give the systematic name of the compound and specify the oxidation state of the transition metal, (ii) draw a crystal field energy-level diagram and assign the d electrons to orbitals, (iii) indicate whether the complex is high-spin or low-spin (for d4 - d7 complexes), and (iv) specify the number of unpaired electrons.

(a) (NH4)[Cr(H2O)6](SO4)2

Textbook Question

For each of the following, (i) give the systematic name of the compound and specify the oxidation state of the transition metal, (ii) draw a crystal field energy-level diagram and assign the d electrons to orbitals, (iii) indicate whether the complex is high-spin or low-spin (for d4 - d7 complexes), and (iv) specify the number of unpaired electrons.

(c) [Ni(NH3)4(H2O)2](NO3)2

Textbook Question

For each of the following, (i) give the systematic name of the compound and specify the oxidation state of the transition metal, (ii) draw a crystal field energy-level diagram and assign the d electrons to orbitals, (iii) indicate whether the complex is high-spin or low-spin (for d4 - d7 complexes), and (iv) specify the number of unpaired electrons. (d) K4[Os(CN)6]

Textbook Question

For each of the following, (i) give the systematic name of the compound and specify the oxidation state of the transition metal, (ii) draw a crystal field energy-level diagram and assign the d electrons to orbitals, (iii) indicate whether the complex is high-spin or low-spin (for d4 - d7 complexes), and (iv) specify the number of unpaired electrons.

(f) Na2[Fe(CO)4]